In 1976, K. Appel, W. Haken and J. Koch at the University of Illinois (USA) gave proof of the four-color conjecture. This conjecture confirms that, the entire geographic map drawn on a plane or a sphere, that each layer occupies a single block (neither colony nor other water in between), can be drawn. just by the color tub so that the two different countries have different colors. The proof of that conjecture was made by calculating 12,000 hours on the most powerful computers; so the human mind cannot verify it and it raises questions about its “math”. In particular, it has stimulated the study of graph theory currently occupying a major place in combinatorial analysis.